Resumen de Linear approximation of approximately linear functions

Igor A. Vestfrid

• Ulam posed the problem: Give conditions in order for a linear mapping near an approximately linear mapping to exist. In this spirit we investigate the stability (local and global) of Jensens functional equation and approximate (in the spirit of John) -rigid maps, -isometries and -quasi-isometries by affine near isometries. In this way we extend one of John's theorems.